1. Field of the Invention
The present invention relates to an electronic manual displaying method and, more particularly, to a method of retrieving a specified word from an electronic manual comprising electronic document data and displaying the document in which the specified word is contained.
2. Description of the Related Art
Recently, owing to the advent of CD-ROM (Compact Disc Read Only Memory), large amounts of document data of a dictionary or a lexicon are converted to electronic data, stored in the CD-ROM, and commercially supplied. Because manuals and other massive documents in a paper version also require extensive space and expense for storage, there has been a need for them to be supplied in a form of electronic data files, i.e., electronic manuals. This contributes to a reduction in space requirements for storage and improves efficiency in transfer of the manuals, by converting the original document data to electronic data and storing the data in a CD-ROM.
On the other hand, a document description language, Standard Generalized Markup Language (SGML), in which a logical structure or semantic structure of the electronic documents is described with simple marks called tags, has been established by the International Standards Organization (ISO). Tagging is carried out by attaching predetermined marks to structurally or semantically important positions such as a title, chapter, item, etc. The SGML document may be used, for example, to prepare an index list by retrieving and extracting the tagged parts. Additionally, because of compliance with the international standard ISO 8879, document data described using SGML may be shared by plural processing devices of different models. In the field of electronic manuals, which are distributed in a mass storage medium such as a CD-ROM capable of storing a large quantity of data, there also is a movement to introduce such a document description language, which is particularly desirable for electronic manuals where retrieval and reference operations are often used.
Conventionally, when a user retrieves a character string of a particular term from document data of an electronic manual stored in a CD-ROM using a computer, in order to start a retrieval operation, he has to select a retrieval function through a keyboard or the like, determine the retrieving direction either forward or backward, then enter the character string to be retrieved, and finally designate execution of the retrieval. The character string is thereby searched for in the retrieval direction from the retrieval starting point, the page where the first detected string is located is displayed on a screen, and a cursor is moved to the position of the retrieved character string. After that, if the continuation of the retrieval operation is designated, another page where the subsequently detected string is located is displayed, and the cursor is moved to the position of the character string. Thus, the character string is retrieved in sequence in the retrieval direction from the retrieval starting point, and every time the retrieved character string is found, the page containing the character string is displayed and the cursor moves to the position of the character string.
However, it is a disadvantage of the conventional retrieval method that when the specified character string is located near the end of a manual, the user has to depress the key many times to continue the retrieval operation until the desired character string is displayed. Another disadvantage of the conventional method is that if the user realizes, during the retrieval operation, that the character string he wants has already been found and displayed but he has failed to stop there, he must begin the retrieval operation again to return to this character string.